Xestospongin C

Xestonspongin C is a structurally novel marine alkaloid isolated from the Okinawan sponge Xestospongia sp. It is a potent, cell-permeable inhibitor of IP3 receptor-mediated Ca2+ release (IC50 = 358 nM). However, since xestospongin C also inhibits voltage-dependent Ca2+ and K+ currents at concentrations similar to those which inhibit the IP3 receptor, it can only be regarded as a selective blocker of the IP3 receptor in permeabilized cells and not in cells with intact plasma membranes. Has vasodilatory properties.